In general, mobile communication systems have been developed to provide communication while securing mobility of users. With the rapid development of technologies, the mobile communication systems have reached a stage of providing high-speed data communication services as well as voice communication.
Currently, a standardization operation for a Long Term Evolution (LTE) system is being progressed as one of the next generation mobile communication systems by the 3rd Generation Partnership Project (3GPP). The LTE system corresponds to a technology, which implements high speed packet-based communication having a maximum transmission rate of 100 Mbps, which is faster than a data transmission rate currently provided, and its standardization has been almost completed.
Recently, discussion about an evolved LTE communication system (LTE-A), in which various new technologies are grafted into the LTE communication system to increase a transmission rate, is progressed in earnest. A representative of the newly introduced technologies may be carrier aggregation. The carrier aggregation uses a plurality of forward carriers and a plurality of backward carriers by one UE (User Equipment) unlike the conventional data transmission/reception using only one forward carrier and one backward carrier by the UE.
The current LTE-A defines only intra-ENB (Evolved NodeB) carrier aggregation. This results in reducing an application possibility of a carrier aggregation function. Particularly, in a scenario overlappingly operating a plurality of pico cells and one micro cell, the macro cell and the pico cells may not be aggregated.